In the case of an electric machine, the conversion of energy generates heat losses which have to be dissipated. When the power of the electric machine is high, specific cooling means are provided that make use, for example, of the flow of a heat-transfer fluid such as oil, for example. The bottom part of the housing forms a reservoir from which the fluid is pumped so as to circulate in parts of the electric machine that are to be cooled. Stator and rotor windings form the parts to be cooled, for example. After flowing through these windings, the fluid returns to the bottom part of the housing in order to remove the heat that it conveys for example by convection against the wall of the housing or into an exchanger provided for this purpose.
It is important to keep the fluid inside the housing and to prevent leaks. To make this possible, it is necessary to provide sealing for the elements situated inside the housing with respect to the outside. The invention relates more particularly to sealing the shaft with respect to the housing. This sealing is difficult to implement on account of the interface between a moving element, in this instance the shaft, and a fixed element, namely the housing.